Fluid Pressure

Fluid pressure refers to a measurement of the force per unit area that acts on an object in the fluid or on a closed container’s surface. Furthermore, the cause of this pressure is due to acceleration, gravity, or by forces that are outside the closed container. The application of the pressure is in all directions because the fluid has no definite shape.

Introduction to Fluid Pressure

Fluid pressure is the pressure at a point within a fluid that arises because of the fluid’s weight. Moreover, the amplification of the fluid pressure can take place through hydraulic mechanisms and changes in the fluid’s velocity.

Consider the case of fluid pressure in a column. Furthermore, in a fluid column, the pressure increases just as the depth increases. Most noteworthy, the reason for this pressure increase is because as one goes deeper, fluid at a lower depth will have to support fluid that is above it.

How do we Measure Fluid Pressure?

When a fluid is at rest, there is an exertion of a force that is perpendicular to any surface in contact with it. This force is known as fluid pressure and it is due to the continuous, random motion of molecules. Furthermore, the measurement of fluid pressure takes place in Pascals (Pa).

An important point to note is that one Pascal is equal to one Newton per square meter (N/m2). Furthermore, fluid pressure is independent of the fluid’s mass. However, its calculation can take with the density and height of the fluid.

Now, one must set up the equation. Furthermore, the equation for this pressure is independent of the liquid’s volume or mass. Moreover, fluid pressure is the product of the liquid’s density, the height of the liquid that is above the object, and gravity.

The height of the liquid is the largest variable in the equation because the gravity and liquid densities are fixed. Furthermore, the fluid pressure formula or equation reads as P_fluid = ρgh, where ρ refers to the liquid’s density, g refers to the acceleration of gravity, and h refers to the liquid’s height (or fluid’s depth).

Next comes the multiplication of the variables. In order to solve the equation, one must take the product of the three variables. For this purpose, a calculator can be used.

For example, consider the case of a fluid with a density of (1.08 x 10³ kg/m³) and it was 5.00 m high. Now, one would multiply (1.08 x 10³ kg/m³) x 9.81 m/s² (acceleration of gravity on Earth) x 5.00 m. Finally, one would attain the answer of 5.30 x 10⁴.

Now one must analyze the results. Furthermore, one must make sure that the results add up logically. Moreover, there must not be reading for negative fluid pressure.

One must also compare different measurements in order to check whether they follow the expected trends. For example, more dense liquids, at the same height, will exert more pressure. Moreover, there will be the exertion of more pressure by the same liquid when the height is higher.

Water is certainly denser than oil. As such, one can expect exertion of more fluid pressure by water in comparison to oil at the same height.

Formula of Fluid Pressure

P_fluid = P + ρgh

where,

P = Pressure at the reference point

P_fluid is the pressure at a point in a fluid

ρ is the fluid’s density

g is the acceleration because of gravity (considering earth g = 9.8 m/s)

h is the height from the reference point

The calculation of the density of the fluid can take place by dividing the fluid’s mass in consideration with the volume of fluid taken.

ρ = m/v

where,

m is the fluid’s mass

v is the fluid’s volume considered

If the fluid is subject to atmospheric pressure, then the total pressure on the system is as

P_fluid = P_o + ρgh

where,

P_o is the atmospheric pressure

FAQs For Fluid Pressure

Question 1: What are the types of fluid pressure?

Answer 1: There are two types of fluid pressure: dynamic pressure and static pressure. Static pressure is the pressure of the fluid which behaves as a potential and the pressure measured turns out to be the same in all directions.

In contrast, dynamic pressure is the pressure of a liquid that is moving. Furthermore, dynamic pressure depends on the direction of motion. Furthermore, dynamic pressure behaves like the flow current.

Question 2: What are the factors that affect fluid pressure?

Answer 2: There are two factors that affect fluid pressure. The first factor is the depth of the fluid: the exertion of the pressure by the fluid increases as the depth increases. The second factor is the density of the fluid: there is the exertion of more pressure by denser fluids like water in comparison to lighter fluids like air.